I often don't feel like I'm not doing "enough" for our community, but then I realize that just being an out trans person right now is enough. I think about what could have been if I'd have had 1 transfemme in my life to show me what could be, and now how I'm already that person for the collection of eggs I've mysteriously collected. These numbers are really heartening and (I'll admit that I'm biased) align with my anecdotal evidence that there's a heck of a lot more of us out there. 💜
I feel like that every day, and I feel a significant sense of guilt over it.
Having just gone past this years Transgender Day of Visibility, and not being out again, I think that you are right. Visibility can go a long way toward helping the community as a whole. I will soon be back out to friends and family, and I hope that will help in some small way for all of us.
Hey Joanne! Tending to yourself and taking the time you need with your transition IS helping the community. Caring for yourself as a trans woman is a radical act, one that serves all of us, regardless of how visible it is.
Transition is scary, and whenever you're ready to take the next step is the right time to do it. You're not failing anyone by going at your pace.
PS I'm really good at giving, but not heeding, my own advice ;-)
I get what you are saying Diana. My problem is that this is not my first rodeo, I came out 20 years ago, transitioned and lived full time for 2 years. To say I was an activist would be an understatement, I was out and proud and told anyone who would listen. There are many reasons why I de-transitioned, some through my own mistakes, others due to family and relationship matters. In any event, the fire is still in my heart, but I am being much more careful to not make the same mistakes I made in the past.
Current events are really making it harder for me to remain quiet though, so only time will tell where I end up. All I know is that it will be a wild ride no matter what happens.
That must have been incredibly hard on you. And to be looking at following your heart again, with everything that's happened over the last 20 years, it must add to the difficulty.
Still, no matter the challenge, I'm glad you're here. 💜
Another heads up about data: the U.S. Census Bureau Data on trans people comes from the PULSE surveys which were intended to study the impact of Covid on different groups. The US 2020 Census does not include questions which can be used to identify trans people.
Last month, the CDC released new data about high school students. It showed the 3.3% of high school students identified as trans, with another 2.2% as questioning. I would think most people identifying as questioning are trans or gender nonconforming. Again, there’s no reason this wouldn’t mirror the population at large, so 5.1% seems to be aligned with this data.
You wrote, "The fact that trans identities are at least partially genetic is not really disputable at this point. Among the most decisive pieces of evidence of this is the incredible rate at which identical twins, whether raised in a single household or separately, are both trans if one is trans...In other words, we have very strong data that says somewhere between a third and a half of what makes a trans person trans comes directly from our DNA."
What is the "strong data" and what does it have to do with twins?
There's a scholarly link right there, and it leads to a summary table of research in a Nature article. Over a dozen studies have found that trans identities are somewhere between 30-50% genetically heritable, as demonstrated by identical twins separated at birth studies.
In a nutshell, we kept an eye on identical twins separated at birth for their lives to see how many of them turned out to be trans (we did this for lots of other stuff too). Because those twins have identical DNA, but different environments, any similarities above the baseline expected level (after complicated stats checks to be sure) are evidence of a genetic basis or predisposition for whatever it is that we're looking for.
In the case of identical twins, when one twin is trans, about 30% of the time the other is too (compared to a background base rate of about 1.6%). So why the range above 30%? Well, that's the statistics engine accounting for outside effects, like social oppression, that would cause a trans person to deny and repress their trans identity.
Fraternal twins share DNA in the way that any two non-identical siblings share DNA--there's a whole range from "very similar" to "really different," based on the quirks of how their parents' DNA recombines, because fraternal twins come from two different eggs.
To answer your question more generally, there are some tentative findings (much less definitive, and I want to be super clear here) that transness, as a genetically heritable thing, runs in families. So, if you have one trans person somewhere in a nuclear family, it's more likely that *anyone* else in that nuclear family would also be trans. Now, what those likelihoods are, I don't have data I'm confident enough in to say; if both parents carry some predisposition to be trans, then their kids might have a higher chance than they did, for instance, and by contrast if one parent was trans and the other cis, the kids would have a much lower chance than the trans parent (who's 100% likely to be trans) or the cis parent (who's unlikely).
This is why we do identical twin studies; we can detect and isolate stuff that's otherwise *hellaciously* difficult to track.
I'm pretty sure that they've shown that one of the causes of being transgender or intersex is an abnormality in the hormonal surges during pregnancy. With the first surge affecting genital expression, and the second brain development. This would also affect identical twins, while not affecting fraternal twins. https://pubmed.ncbi.nlm.nih.gov/21962724/
Unfortunately, that study was rolled into the big brain structure metastudy I linked in the body of the article. The results, in the end, did not pan out on the macro level.
From what I understand, that study only applies to the macro scale parts of the brain. While there are, and have been for quite some time, known dimorphic parts of the brain. The thing is, that these parts of the brain are small compared to the larger. Parts of the brain that were measured for the large meta study. (the insula is one such region https://psychcentral.com/news/2018/03/16/structural-brain-differences-for-transgender-people#2) IIRC, the scientists that did the big metastudy took pains to point out that their study didn't say there were no dimorphic differences in the brain. Just that there were none for any of the big things that are ascribed to sexual differences (spacial perception, reasoning, creativity, etc.) There used to be a big article on the research to date for transgender people. But the publishers took it down when it started being used to promote transphobia.
No, the study points out that total, size-adjusted differences in the brain amount to less than 2% of total structural brain differentiation. And the pains you're noting are very standard scientific boilerplate to recognize the 2% they *did* find, which was *in situ*, not idealized--meaning that it's almost certainly the result of lived experience (for instance, TBI is much more likely in men than women), but they can't prove it conclusively.
Here's something to consider, if in 1905 they did a representative study of peoples brains to see if there was any difference between left and right handed people. Would they have found a significant proportion of right handed people had brain differences similar to those who are left-handed, and then claimed that those differences just didn't exist?
Do I think they will ever be able to look at a newborn brain and tell you their gender and sexual orientation? No. Do I think they could give you an 80:20 probability? Yes. But by that point, I don't think they'd bother looking as it wouldn't matter anyway.
I am glad that you responded to this. When I first came out and transitioned 20 years ago, it was that particular study that I used with my friends and family, and honestly for myself as well. My thought was that if there was a medical reason for my gender issues, the I was not as insane as I thought I was. I will not go into how flawed that line of thought was, but at the time it worked for me.
Hello! So! I love your blog but I am thrilled to report that you have the New Zealand stat wrong! that data was from a Household Economic Survey, which covers maybe 1% of all households, chosen at random. Our last actual census was 2018 and had serious issues around accessibility for marginalized groups, and the 2023 census that we hope has fixed those issues is being processed now. The 2023 census is also the first one to contain questions about gender identity, trans status, and sexuality, so a lot of LGBTQ+ people here are super excited for the results of that.
Holy cow, you're not kidding on that wait time! I'll try and get things updated today or tomorrow (it's a work day and my anniversary celebration, respectively, so I'm slammed).
I often don't feel like I'm not doing "enough" for our community, but then I realize that just being an out trans person right now is enough. I think about what could have been if I'd have had 1 transfemme in my life to show me what could be, and now how I'm already that person for the collection of eggs I've mysteriously collected. These numbers are really heartening and (I'll admit that I'm biased) align with my anecdotal evidence that there's a heck of a lot more of us out there. 💜
Hi Diana
I feel like that every day, and I feel a significant sense of guilt over it.
Having just gone past this years Transgender Day of Visibility, and not being out again, I think that you are right. Visibility can go a long way toward helping the community as a whole. I will soon be back out to friends and family, and I hope that will help in some small way for all of us.
Hey Joanne! Tending to yourself and taking the time you need with your transition IS helping the community. Caring for yourself as a trans woman is a radical act, one that serves all of us, regardless of how visible it is.
Transition is scary, and whenever you're ready to take the next step is the right time to do it. You're not failing anyone by going at your pace.
PS I'm really good at giving, but not heeding, my own advice ;-)
Solid agree on every word of this.
I get what you are saying Diana. My problem is that this is not my first rodeo, I came out 20 years ago, transitioned and lived full time for 2 years. To say I was an activist would be an understatement, I was out and proud and told anyone who would listen. There are many reasons why I de-transitioned, some through my own mistakes, others due to family and relationship matters. In any event, the fire is still in my heart, but I am being much more careful to not make the same mistakes I made in the past.
Current events are really making it harder for me to remain quiet though, so only time will tell where I end up. All I know is that it will be a wild ride no matter what happens.
That must have been incredibly hard on you. And to be looking at following your heart again, with everything that's happened over the last 20 years, it must add to the difficulty.
Still, no matter the challenge, I'm glad you're here. 💜
Thanks, I am glad to be here, and doubly glad that I have a second chance to be my genuine self.
Another heads up about data: the U.S. Census Bureau Data on trans people comes from the PULSE surveys which were intended to study the impact of Covid on different groups. The US 2020 Census does not include questions which can be used to identify trans people.
This his one heck of an article. Thank you!
Last month, the CDC released new data about high school students. It showed the 3.3% of high school students identified as trans, with another 2.2% as questioning. I would think most people identifying as questioning are trans or gender nonconforming. Again, there’s no reason this wouldn’t mirror the population at large, so 5.1% seems to be aligned with this data.
I saw that CDC data--it's an almost exact doubling of their 2019 headcount. So... Yeah. We rise!
Hi Zoe. Thanks for this article.
You wrote, "The fact that trans identities are at least partially genetic is not really disputable at this point. Among the most decisive pieces of evidence of this is the incredible rate at which identical twins, whether raised in a single household or separately, are both trans if one is trans...In other words, we have very strong data that says somewhere between a third and a half of what makes a trans person trans comes directly from our DNA."
What is the "strong data" and what does it have to do with twins?
There's a scholarly link right there, and it leads to a summary table of research in a Nature article. Over a dozen studies have found that trans identities are somewhere between 30-50% genetically heritable, as demonstrated by identical twins separated at birth studies.
Thanks for responding.
Yes, I saw the link but I wasn't sure what I was looking at. That's why I really like your site; you do such a great job breaking down the jargon.
How do the twin birth studies show that trans identities are "somewhere between 30-50% genetically heritable"?
Thanks for taking time to help me understand!
In a nutshell, we kept an eye on identical twins separated at birth for their lives to see how many of them turned out to be trans (we did this for lots of other stuff too). Because those twins have identical DNA, but different environments, any similarities above the baseline expected level (after complicated stats checks to be sure) are evidence of a genetic basis or predisposition for whatever it is that we're looking for.
In the case of identical twins, when one twin is trans, about 30% of the time the other is too (compared to a background base rate of about 1.6%). So why the range above 30%? Well, that's the statistics engine accounting for outside effects, like social oppression, that would cause a trans person to deny and repress their trans identity.
Hope this helps!
Yes, this does help.
I read your comment as soon as you posted it but my brain just barely understood it.
I'm slow sometimes. :)
What about fraternal twins? Do they share the same DNA? Do scientists see the same percentage?
Thank you!
Fraternal twins share DNA in the way that any two non-identical siblings share DNA--there's a whole range from "very similar" to "really different," based on the quirks of how their parents' DNA recombines, because fraternal twins come from two different eggs.
To answer your question more generally, there are some tentative findings (much less definitive, and I want to be super clear here) that transness, as a genetically heritable thing, runs in families. So, if you have one trans person somewhere in a nuclear family, it's more likely that *anyone* else in that nuclear family would also be trans. Now, what those likelihoods are, I don't have data I'm confident enough in to say; if both parents carry some predisposition to be trans, then their kids might have a higher chance than they did, for instance, and by contrast if one parent was trans and the other cis, the kids would have a much lower chance than the trans parent (who's 100% likely to be trans) or the cis parent (who's unlikely).
This is why we do identical twin studies; we can detect and isolate stuff that's otherwise *hellaciously* difficult to track.
What does "background base rate of about 1.6%" mean?
I'm pretty sure that they've shown that one of the causes of being transgender or intersex is an abnormality in the hormonal surges during pregnancy. With the first surge affecting genital expression, and the second brain development. This would also affect identical twins, while not affecting fraternal twins. https://pubmed.ncbi.nlm.nih.gov/21962724/
Unfortunately, that study was rolled into the big brain structure metastudy I linked in the body of the article. The results, in the end, did not pan out on the macro level.
From what I understand, that study only applies to the macro scale parts of the brain. While there are, and have been for quite some time, known dimorphic parts of the brain. The thing is, that these parts of the brain are small compared to the larger. Parts of the brain that were measured for the large meta study. (the insula is one such region https://psychcentral.com/news/2018/03/16/structural-brain-differences-for-transgender-people#2) IIRC, the scientists that did the big metastudy took pains to point out that their study didn't say there were no dimorphic differences in the brain. Just that there were none for any of the big things that are ascribed to sexual differences (spacial perception, reasoning, creativity, etc.) There used to be a big article on the research to date for transgender people. But the publishers took it down when it started being used to promote transphobia.
No, the study points out that total, size-adjusted differences in the brain amount to less than 2% of total structural brain differentiation. And the pains you're noting are very standard scientific boilerplate to recognize the 2% they *did* find, which was *in situ*, not idealized--meaning that it's almost certainly the result of lived experience (for instance, TBI is much more likely in men than women), but they can't prove it conclusively.
Oh, and here's the original link to the article I was talking about (sorry it took so long to find, I had to go digging through my e-mails to find a link). They've helpfully also provided links to useful studies. https://sitn.hms.harvard.edu/flash/2016/gender-lines-science-transgender-identity/
So, even after that study came out, there are still conclusive tendencies in brains. https://www.psychologytoday.com/us/blog/your-brain-food/202204/do-ancient-brain-regions-help-define-our-sexual-orientation#:~:text=1%20Heterosexuals%20have%20a%20bigger%20thalamus%20and%20motor,at%20birth%2C%20have%20a%20smaller%20putamen.%20More%20items
Here's something to consider, if in 1905 they did a representative study of peoples brains to see if there was any difference between left and right handed people. Would they have found a significant proportion of right handed people had brain differences similar to those who are left-handed, and then claimed that those differences just didn't exist?
Do I think they will ever be able to look at a newborn brain and tell you their gender and sexual orientation? No. Do I think they could give you an 80:20 probability? Yes. But by that point, I don't think they'd bother looking as it wouldn't matter anyway.
I am glad that you responded to this. When I first came out and transitioned 20 years ago, it was that particular study that I used with my friends and family, and honestly for myself as well. My thought was that if there was a medical reason for my gender issues, the I was not as insane as I thought I was. I will not go into how flawed that line of thought was, but at the time it worked for me.
Hello! So! I love your blog but I am thrilled to report that you have the New Zealand stat wrong! that data was from a Household Economic Survey, which covers maybe 1% of all households, chosen at random. Our last actual census was 2018 and had serious issues around accessibility for marginalized groups, and the 2023 census that we hope has fixed those issues is being processed now. The 2023 census is also the first one to contain questions about gender identity, trans status, and sexuality, so a lot of LGBTQ+ people here are super excited for the results of that.
Oh, that's wonderful and exciting! Please do poke me when the data goes live, and I'll get the article updated.
It took a while (A WHILE) but the data's live here now - https://www.stats.govt.nz/news/2023-census-shows-1-in-20-adults-belong-to-aotearoa-new-zealands-lgbtiq-population/ - 0.7% of New Zealanders are trans and felt comfortable reporting that in the census. (4.9% are LGBTQ+ broadly.)
The mills of Stats NZ grind slowly but they grind exceeding small, and all that.
Holy cow, you're not kidding on that wait time! I'll try and get things updated today or tomorrow (it's a work day and my anniversary celebration, respectively, so I'm slammed).
Congrats on the anniversary!